The processes of amine uptake and amine storage, and the number and composition of platelet storage vesicles, are examined utilizing radiolabelled tracers, transmission electron microscopy, and electron microprobe X-ray analysis. Synchrotron radiation is used to study the fine structure of the calcium in various model systems. The studies have three principal objectives: (1) quantitation of amine uptake, and of the number and composition of storage vesicles in platelets following treatment with various psychoactive drugs and releasing agents; (2) evaluation of the mechanisms responsible for amine movement across membranes; (3) examination of the chemical and physical environment of storage vesicles.